Device for regulating the source of electric energy on a hybrid electric vehicle

ABSTRACT

Device for regulating the source of electric energy on a hybrid electric vehicle comprising at least an electric motor for driving the driving wheels of the vehicle and supplied with current by said source of energy and a generating set comprising a heat engine with which there is associated a current generator supplying current to said source of electric energy. This device comprises a circuit for determining the state of charge of the source of electric energy, a circuit for controlling the excitation winding of the generator of the generating set in accordance with the state of charge of said source, and a logic circuit for operating and stopping the heat engine and controlled by said circuit determining the state of charge of said source of electric energy.

The present invention relates to a device for regulating the source ofelectric energy on a hybride or mixed-drive electric vehicle comprisingat least an electric motor for driving the driving wheels of the vehicleand supplied with current by said source of energy and a generating setcomprising a heat engine with which there is associated a currentgenerator supplying current to said source of electric energy.

A regulating device of this general type is disclosed in Swiss Pat. No.479,418. This device comprises a circuit for determining the state ofcharge of the battery and an automatic device for operating and stoppingthe heat engine driving a generator.

The object of the invention is to provide a regulating device forregulating the source of electric energy on a hybride electric vehiclehaving driving wheels, comprising at least an electric motor for drivingthe driving wheels of the vehicle and supplied with current by saidsource of energy, and a generating set comprising a heat engine and acurrent generator which has an excitation winding and is combined withthe heat engine and a first circuit connecting the generator to saidsource for supplying current to said source, a second circuit fordetermining the state of charge of said source, a device for operatingand stopping the heat engine, and a third circuit associated with theexcitation winding of the generator for controlling said winding as afunction of the state of charge of said source, the device for operatingand stopping the heat engine comprising a logic circuit controlled bysaid second circuit.

Further features of the invention will be apparent from the ensuingdescription with reference to the accompanying drawings which are givensolely by way of example:

FIG. 1 is a block diagram of the regulating device according to theinvention;

FIG. 2 is a more detailed electric circuit diagram of the excitationcircuit of the alternator of the device shown in FIG. 1;

FIG. 3 is an electric diagram of the circuit for regulating theexcitation circuit shown in FIG. 2;

FIG. 4 is a logic circuit of the detection of the state of the batteryof the device shown in FIG. 1;

FIG. 5 is a diagram showing the signals at certain points of the circuitshown in FIG. 4;

FIG. 6 shows an embodiment of the control logic of the starter of thedevice shown in FIG. 1;

FIG. 7 is a diagram showing the signals at certain points of the circuitshown in FIG. 6;

FIG. 8 shows an embodiment of the logic circuit for stopping the heatengine, and

FIG. 9 is a diagram showing the form of the signals at a number ofpoints of the circuit shown in FIG. 8.

The device shown in FIG. 1 is a device for regulating the source ofelectric energy of a hybrid electric vehicle whose driving wheels 1 aredriven by an electric driving motor 2 supplied with current by a battery3 the charging of which is ensured by an alternator 4 which is driven bya heat engine 5, said alternator being connected to the battery 3through a rectifier unit 6.

The electric motor 2 is connected to the battery through a controlcircuit 7 on which the user may act by means of an accelerator pedal 8and a brake pedal 9.

The alternator 4 comprises an excitation winding 10 controlled by anexcitation circuit 11 which is connected to the terminals of the battery3 and is itself controlled by a circuit 12 which ascertains the state ofthe battery 3.

A heat engine 5 is associated with a starter 13 which is supplied withcurrent by a separate battery 14 to which it is connected in series witha switch 15 controlled by a relay coil 16 connected to a logic circuit17 for stopping and operating the engine 5.

The circuit shown in FIG. 2 is the excitation circuit of the alternator.

The excitation winding 10 of the alternator is connected in series witha thyristor 18 to the terminals of the battery 3, the cathode of thethyristor being connected to the negative terminal of the battery.

The anode of the thyristor 18 is connected at the common points of adiode 19 and a capacitor 20 which are connected in series to theterminals of the battery 3.

The thyristor 18, the diode 19 and the capacitor 20 constitute a signalgenerator.

Connected in parallel with the diode 19 and the capacitor 20 is athermal protection thyristor 21, whereas connected to the terminals ofthe capacitor 20 there is a voltage divider 22 whose intermediateterminal is connected to the output 23 of the charge safety.

The circuit is completed by a fuse 24 which is connected in series withthe excitation winding 10.

The regulating circuit shown in FIG. 3 comprises mainly a voltagedivider 26 connected to the positive terminal of the battery 3 and to asource of negative voltage, for example -15 V.

This voltage divider 26 comprises a potentiometer 27 whose slide isconnected to an input of a differential amplifier 28 also connectedthrough a conductor 29 to an excitation stopping control circuit (notshown). The other input of the amplifier 28 is connected to earththrough a resistor 30. The output of the amplifier 28 is connected tothe base of a P-N-P transistor 31 which is connected to a positivesource of voltage of, for example +5 V through a diode 32.

The emitter of the transistor 31 is connected to a source of positivevoltage, for example +15 V, through a resistor 32^(a) whereas thecollector thereof is connected to a source of negative voltage through acapacitor 33.

The collector of the transistor 31 is also connected to the controlelectrode of the unijunction transistor 34 which is moreover connectedbetween a source of positive voltage and a source of the same type ofnegative voltage through resistors 35, 36 and 37 respectively.

Connected in a series to the terminals of the resistor 37 are a resistor38 and a primary winding 39 of a transformer 40 whose secondary winding41 is connected to the control electrode of the thyristor 18 of thecircuit shown in FIG. 2.

FIG. 4 shows in the logic form the circuit for determining the state ofthe battery shown at 12 in FIG. 1.

This circuit comprises mainly two voltage dividers 42 and 43 which areconnected in parallel to the positive terminal of the battery 3.

Each divider comprises a potentiometer 44, 45 whose slide is connectedto an input of a corresponding comparator 46, 47.

The comparator 46 is adapted to designate the low level of the voltageof the battery whereas the comparator 47 is adapted to designate thehigh level by means of a stable reference voltage U_(ref) applied to theterminals of the two voltage dividers 42, 43 opposed to those connectedto the battery.

The other inputs of the comparators 46 and 47 are connected to earththrough corresponding resistors 48, 49.

The output of the comparator 46 is connected to a memory 50 comprising,in the presently-described embodiment, an inverter 51, an inverting ANDgate having two inputs 52, one of which is connected to the output ofthe inverter 51, an inverting AND gate 53 having three inputs one inputof which is connected to the output of the gate 52 and an output whichis connected to the input of another inverter 54.

The output of the gate 53 is furthermore re-injected into the input ofthe gate 52 which is other than that connected to the gate 51.

The gate 53 further comprises an input connected to the positiveterminal of the battery and an input connected to the output of an addercircuit 55 formed by an inverter 56 connected to the output of thecomparator 47 and an inverting AND gate 57 connected between theinverter 56 and the gate 53 of the membory 50.

The output of the comparator 47 is furthermore connected, through acapacitor 58 and a diode 59 in series, to an input of a monostablecircuit 60 whose output is connected, through an inverter 61, to theother input of the gate 57 of the adder circuit 55.

The output of the inverter 54 of the membory 50 constitutes the stateoutput of the battery for connection to the circuit 17 of the deviceshown in FIG. 1.

It is connected to the base of a transistor 62 whose collector isconnected to the conductor 29 of the amplifier 28 of the circuit shownin FIG. 3.

The circuit shown in FIG. 6 comprises a clock input 63, a battery stateinput 64, an alternator voltage input 65 and an alternator temperatureinput 66.

The clock input 63 is connected to an input of an inverting AND gate 67having three inputs of which another input is connected to the batterystate input 64, the output of the gate 67 being connected to an input ofa monostable circuit 68 through a capacitor 69 and a diode 70 in series.

The output of the circuit 68 is connected to an input of an invertingAND gate having four inputs 71 the three other inputs of which areconstituted by the inputs 64, 65 and 66 of the circuit.

The output of the circuit 68 is furthermore connected to the input of amonostable circuit 72 through a capacitor 73 and a diode 74 andconnected directly to the input of an inverter 75. The output of thecircuit 73 is connected to an input of an inverting AND gate 76 throughan inverter 77 whereas the output of the inverter 75 is directlyconnected to the other input of the gate 76.

The output of the gate 76 is connected to the third input of the gate 67through an inverter 78.

The output of the AND gate 71 having four inputs is connected to thebase of a transistor 79 through an inverter 80.

The emitter-collector circuit of the transistor 79 is connected inseries with a winding 81 of a relay 82 controlling the starter 13 of theheat engine 5 (FIG. 1).

The circuit shown in FIG. 8 is the circuit controlling the stopping ofthe heat engine in accordance with the state of the battery 3.

This circuit comprises mainly an input connected to the output of thecircuit 12 determining the state of the battery 3 shown in FIG. 1 or, tothe output of the circuit shown in FIG. 4 which is an embodiment of thecircuit 12 shown in FIG. 1.

The input of the circuit shown in FIG. 8 is connected to an input of amonostable circuit 83 through a capacitor 84 and a diode 85 connected inseries. The output of the circuit 83 is connected through an inverter 86to an input of an inverting AND gate 87 having two inputs. The otherinput of the gate 87 is connected to the input of the circuit through aninverter 88 whereas its output is connected to the base of a transistor89 whose emitter collector path is connected to the terminals of asource of direct voltage in series with the winding 90 of a relay 91controlling the stopping of the heat engine 5 (FIG. 1).

The input of the circuit is connected in a similar manner through acapacitor 84 and a diode 92 to the input of a second monostable circuit93 whose triggering threshold is lower than that of the circuit 83.

The output of the circuit 93 is connected to an input of a gate 94having two inputs the other input of which is connected to the output ofthe inverter 88 and the output of which is connected through an inverter95 to the base of a transistor 96 whose emitter-collector path isconnected in series with the winding 97 of a relay 98 controlling theidling speed of the heat engine 5.

The relays 91 and 98 are both inserted in the circuit of the battery ofthe heat engine.

The device just described operates in the following manner:

The battery 3 of the device shown in FIG. 1 has to be maintained in astate for supplying the peak driving power for driving the motor 2.

This peak power must be able to be supplied when the state of thebattery is between a high level corresponding to a 20% discharge and alow level corresponding to a 80% discharge.

It is therefore necessary to permanently supervise the voltage of thebattery so as to start up the generating set constituted by the heatengine 5 the alternator 4 and the rectifiers 6 as soon as the battery 3reaches the aforementioned low level.

The output of the alternator is a function of the voltage across theterminals of the battery which pilots the regulation of the excitationof the alternator in a manner which will be described with reference toFIGS. 2 and 3.

The thyristor 18 regulates the current of the excitation winding 10 ofthe alternator. For this purpose, it is triggered by the circuit 12determining the state of the battery shown in FIG. 1.

If the temperature of the alternator is too high, the thyristor 21 istriggered and causes the fuse 24 to melt which breaks the supply circuitof the winding 10.

The regulation of the excitation of the alternator wil now be describedwith reference to FIG. 3.

In a first stage, the alternator 4 charges the battery 3 with constantexcitation and follows its external characteristic, the generating setoperating at constant speed.

The base of the transistor 31 of the circuit shown in FIG. 3 is blockedat a positive voltage which is applied thereto through the diode 32. Thecapacitor 33 charges and discharges at a constant rhythm in theunijunction component 34 which triggers the thyristor 18 (FIG. 2)through the transformer 40 and consequently the supply of current to theexcitation winding 10 of the alternator.

The excitation current is therefore constant.

As the battery 3 is being charged, the voltage U_(B) increases.

The amplifier 28 amplifies the difference between the voltage of thebattery and a constant voltage applied to the opposite terminals of thevoltage divider 26.

The base of the transistor 31 increases in voltage so that the currentof the collector of the transistor decreases and the capacitor 33 ischarged more slowly. Consequently, the relaxation frequency decreases inthe same way as the intervals of conduction of the thyristor 18.

Consequently, the excitation of the alternator 4 is decreased so thatthe charging current of the battery decreases and can be cancelled outif the voltage of the battery becomes sufficient.

The maximum value of the excitation current so regulated is such thatthe heat engine is never overloaded.

The circuit 12 for determining the state of the battery must furnish theinformation of the state of the battery 3 to the excitation circuit 11of the alternator and also to the logic circuit 17 for operating andstopping the heat engine 5 of the generating set.

This circuit is shown in FIG. 4 and the operation thereof will now bedescribed with reference to FIGS. 4 and 5.

The two comparators 46 and 47 respectively detect the low level and highlevel of the voltage U_(B) of the battery 3 by means of a stablereference voltage U_(ref).

When the voltage of the battery is lower than the low level given by thedivider 42, the comparator 46 delivers at its output a positive voltagewhich passes through the memory 50 so that at the output of the latterthere appears a logic signal E=1 indicating that the battery 3 must berecharged.

This signal is applied to the engine operating and stopping circuit 14the operation of which will be described hereinafter.

As the charge level of the battery 3 increases, the voltage U_(B)increases and the comparator 46 delivers a negative voltage which doesnot affect the state E since the memory 50 retains the firstinformation.

When the upper level, corresponding to the practically fully chargedbattery, is reached, the comparator 47 delivers a negative voltage. Themonostable circuit 60 stores the information during several seconds andthe adder 55 only allows through the information if the comparator 47has not changed state during this time of storage of the information bythe circuit 60 (FIG. 5).

Such an operation is rendered necessary in order that in the course of aregenerative braking which raises the voltage of the battery, thegenerating set is not made to stop.

When the adder 55 allows through the information relating to the highlevel reached by the battery, the memory 50 changes state so that alogic state E=0 appears at its output and causes the stoppage of thegenerating set through the circuit shown in FIG. 8.

The logic circuit controlling the starter 13 of the device shown in FIG.1 is illustrated in FIG. 6.

To actuate the starter, three conditions must be satisfied.

The voltage of the alternator 4 must be zero, which shows that thegenerating set does not operate.

The temperature of the alternator must be lower than a dangerous valuefor the machine.

The state of the battery must be such that the battery must be charged.This state corresponds to E=1 at the output of the circuit shown in FIG.4.

The operation of the circuit shown in FIG. 6 is illustrated by thediagram of FIG. 7.

The purpose of the circuit 68 is to control the duration of the startingup. The circuit 72 is adapted to control the time which elapses betweentwo consecutive startings.

The gate 71 controls the starter 13 (FIG. 1) when the threeaforementioned conditions are satisfied and the starting order istransmitted by the circuit 68.

This order can only reach the winding 81 of the relay 82 if the signalE=1 is at the input 64 of the circuit shown in FIG. 6.

Permission to start or to re-start is given by the gate 76.

This permission can only be given by the circuit 72 for the firststarting and thereafter if the time or pause between two consecutivestartings has elapsed.

When the output of the circuit shown in FIG. 4 changes to the state E=0indicating that the battery 3 of the vehicle is sufficiently charged,the heat engine 5 of the generating set must be stopped.

The circuit shown in FIG. 8 ensures this stopping. When the input signalE of this circuit changes to the logic 0 state, the output of thecircuits 93 and 83 changes to the logic 1 state (FIG. 9).

The output signal of the circuit 83 is inverted by the inverter 86 andthen applied to the gate 87 which receives at its other input the signalE inverted by the inverter 88.

During the presence at its inputs of the two aforementioned signals, thegate 87 produces a signal which prevents the supply of current to thewinding 90 of the relay 91. Simultaneously, the state E of the input ofthe circuit is applied to the input of the monostable circuit 93 whichchanges to 1 state. Its output signal is applied to an input of the gate94 which receives at its other input the signal E which is inverted andin turn produces a signal which, after inversion by the inverter 95,causes the supply of current to the winding 97 of the idling speed relay98.

The closing time of the relay 98 exceeds the closing time of the relay91 so that before the engine stopping signal appears at S (FIG. 9), agiven interval of time elapses in the course of which the heat engine 5operates at idling speed.

Upon stoppage of the heat engine, the battery 3 supplies current to themotor 2 until its discharge requires a new intervention on the part ofthe generating set.

At this moment, the cycle of operation of the regulating device isresumed.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:
 1. A regulating device for regulating thesource of electric energy on a hybrid electric vehicle having drivingwheels, comprising at least an electric motor for driving the drivingwheels of the vehicle and supplied with current by said source ofenergy, and a generating set comprising a heat engine and a currentgenerator which has an excitation winding and is combined with the heatengine and a first circuit connecting the generator to said source forsupplying current to said source, a second circuit for determining thestate of charge of said source, a device for operating and stopping theheat engine, and a third circuit associated with the excitation windingof the generator for controlling said winding as a function of the stateof charge of said source, the device for operating and stopping the heatengine comprising a logic circuit controlled by said second circuit,wherein said second circuit comprises means providing a referencevoltage and means for detecting a low level and means for detecting ahigh level of the voltage of said source relative to said referencevoltage, means for memorizing an electric signal corresponding to alevel of voltage of said source which is lower than said low level andmeans for erasing the information contained in said memory connected toan output of said means for detecting the high level of a voltage of thesource of energy.
 2. A device as claimed in claim 1, wherein said meansfor detecting the high and low levels of the voltage of said sourcecomprise a voltage divider which is connected between said source andthe means providing the reference voltage, and comparators each havingan input which is connected to the voltage divider.
 3. A device asclaimed in claim 1, wherein said means for erasing the information ofthe low level contained in said memory comprise an adder having an inputconnected directly to an output of said means for detecting the highlevel and another input connected to the output of said means fordetecting the high level through a circuit storing the information ofthe low level during a predetermined period of time.
 4. A device asclaimed in claim 1, wherein said third circuit comprises a controlledrectifier having a control electrode and connected in series with saidexcitation winding and a circuit for regulating the excitation of thegenerator and connected to the control electrode of the controlledrectifier, the circuit for regulating the excitation comprising atransistor having a base, an emitter, a collector and anemitter-collector path, a capacitor, a unijunction transistor, atransformer, a voltage divider having a moving terminal and fixedterminals, means providing a reference voltage, a differential amplifierhaving an input connected to the moving terminal of the voltage dividerand an output, the fixed terminals of the voltage divider beingrespectively connected to said source and to the means providing thereference voltage, the output of the amplifier being connected to thebase of the transistor whose emitter-collector path is connected inseries with the capacitor, the collector of the transistor beingconnected to the unijunction transistor which is itself connected to thecontrol electrode of the control rectifier through the transformer.
 5. Adevice as claimed in claim 4, comprising a fuse interposed between saidsource and the excitation winding of the generator, a thyristor forthermal protection of the alternator connected in parallel with theexcitation winding of the generator and the controlledrectifier,conduction of the thermal protection thyristor causing theopening of said fuse.
 6. A device as claimed in claim 1, comprising astarter for the heat engine, the device for operating and stopping theheat engine comprising a logic circuit combined with the starter of theheat engine for controlling the starter as a function of the state ofsaid source, of the output voltage of the generator and of thetemperature of said generator, and a logic circuit for stopping the heatengine when the state of charge of said source has reached apredetermined level, said device further comprising a supply circuit forthe starter, a relay for closing said supply circuit, said logic circuitfor controlling the starter comprising a first monostable circuit forcontrolling the duration of the starting effectd by the starter, asecond monostable circuit for controlling an interval of time betweentwo consecutive startings and an AND gate for controlling the starterwhen the voltage of the generator is zero and the temperature of thegenerator is lower than a predetermined value and the state of thecharge of said source requires a starting up of the heat engine, saidAND gate controlling said supply circuit for the starter.
 7. A device asclaimed in claim 6, wherein the logic circuit for stopping the heatengine comprises a first monostable circuit for forming an interval oftime during which the heat engine must operate at idling speed, a gatehaving an input connected to the monostable circuit and an inputconnected to state of charge input of said source, the output signal ofsaid gate constituting an order to operate the heat engine at idlingspeed and a second monostable circuit having an output and for formingan interval of time less than the interval of time formed by the firstmonostable circuit, a second gate having an input connected to theoutput of the second monostable circuit and an input connected to thestate of charge input of said source, the output signal of the secondgate constituting an order to stop the heat engine.